GaN Substrate Nitride Interface Layer for Low-Defect Epitaxy
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Solution Overview
Problem
Current methods for manufacturing semiconductor substrates based on group 13 nitride materials, such as gallium nitride (GaN), suffer from high defect densities, cracking, and inhomogeneity due to lattice mismatch and thermal expansion coefficient differences with traditional substrates like sapphire, silicon, and silicon carbide, which degrade the performance of electronic components.
Innovation Solution
A method involving the deposition of a separation layer with elements like Ge, Zr, Y, Si, B, Sc, Mg, In, W, La, Ti, Ta, Hf, and Hf, followed by an interface layer of AlxOyNz and a nucleation layer of AlrGasIntNu, to improve crystal quality and reduce defects, using techniques like MOVPE, HVPE, and ALD, resulting in a self-supporting GaN layer with reduced misorientation and improved homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If heteroepitaxy is used to grow GaN on sapphire, silicon, or SiC substrates, then semiconductor components can be manufactured, but high defect densities and cracking occur due to lattice mismatch and thermal expansion coefficient differences
Solution Approach 1:
The patent introduces a nucleation layer as an intermediary between the substrate and the GaN epitaxial layer. This nucleation layer serves as a mediator that reduces the lattice mismatch and thermal expansion coefficient differences, thereby decreasing defect density and cracking while maintaining the manufacturability of semiconductor components on conventional substrates.
Solution Approach 2:
The patent employs composite material structures consisting of multiple layers including the substrate, nucleation layer, and GaN epitaxial layer. Each layer is specifically designed with particular material properties to address the interface problems, creating a composite structure that overall reduces defects while enabling component manufacturing.
2Manufacturing precision
If a nucleation layer is inserted between the substrate and GaN epitaxial layer, then defect density is reduced, but the process complexity increases
Solution Approach 1:
The nucleation layer is deposited in advance, before the GaN epitaxial layer growth, to prepare a suitable interface that reduces defects. This preliminary action of creating the nucleation layer with specific crystal orientation and material properties enables subsequent high-quality GaN growth while managing process complexity through structured sequencing.
3Length of stationary object
If thick GaN layers are grown to achieve desired component thickness, then component functionality is improved, but cracking and inhomogeneity increase
Solution Approach 1:
The nucleation layer is prepared in advance to establish a defect-free foundation before growing thick GaN layers. This preliminary structuring enables subsequent growth of thicker layers with improved homogeneity and reduced cracking by ensuring uniform stress distribution from the base interface.
Solution Approach 2:
The patent utilizes controlled changes in growth parameters during epitaxy, including temperature, pressure, and gas flow rates, to manage stress and defect propagation in thick GaN layers. By dynamically adjusting these parameters during the growth process, homogeneous thick layers with reduced cracking are achieved.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces GaN wafers with low defect density, reduced cracking, and enhanced electrical resistivity uniformity, achieving a smooth, continuous surface with improved crystal quality and mechanical stability, suitable for optoelectronic and electronic components.
Implementation Method 1
depositing, by epitaxial growth, at least one nucleation layer of formula AlrGasIntNu
Implementation Method 2
laser ablation which can decompose the GaN at the interface with the sapphire substrate
Implementation Method 3
chemical attack of the substrate supporting the layer of a group III element which can also be used during the growth or after the epitaxial growth of the layer
Data Source
AI summary
Disclosed is a method for manufacturing a monocrystalline semiconductor material of the nitride of a group 13 element, comprising a step of depositing at least one separation layer comprising an element M selected among Ge, Zr, Y, Si, Se, Sc, Mg, In, W, La, Ti, Ta and Hf, by epitaxial growth on a starting substrate; characterised in that an interface layer of formula MvAlxOyNz is deposited between the starting substrate and the separation layer, wherein: —the atomic indices x and z are greater than 0 and less than or equal to 1; and, —the atomic indices v and y are between 0 and 1; and—the sum y+z is greater than 0.9 and less than or equal to 1.5; and—the sum v+y is greater than or equal to 0.3 and less than or equal to 1.